1. Field of the Invention
This invention relates to a TTL automatic flash control camera capable of effecting TTL multi-flash control.
2. Related Background Art
A camera system capable of effecting TTL automatic flash control has heretofore been such that in a camera body, a light receiving element is disposed at a location facing the whole or main portion of the surface of film and after a shutter interposed between the surface of the film and the light receiving element is fully opened, a flash apparatus is caused to start flashing and light created by the image of the object field being reflected by the surface of the film is photoelectrically converted by the light receiving element and a signal corresponding to the integrated amount of the quantity of light is compared with a predetermined value, whereby the quantity of emitted light of the flash apparatus is controlled so that predetermined brightness may be provided on the surface of the film. The disadvantage of this system is that the detection area of the object field is monistic and therefore various situations of the object field cannot be coped with and the exposure of the main object the photographer desires to photograph does not become proper. Some techniques for solving this problem have been developed in recent years.
As one of them, U.S. application Ser. No. 560,745 (filed on Jul. 31, 1990) based on Japanese Patent Application No. 1-203735 proposes, the following automatic flash control, the following system adopting the concept of multi-pattern photometry. A plurality of photoelectric converters capable of dividing the object field into a plurality of areas and metering these areas are disposed at locations facing the surface of film and immediately before a focal plane shutter interposed between the surface of the film and the plurality of photoelectric converters, a flash apparatus is caused to effect preliminary flashing and light created by the object image by the flashlight being reflected by the surface of a shutter curtain is caught by the plurality of photoelectric converters and the outputs thereof severally integrated are detected as the object field reflected light distributions of the respective areas by the flashing. The detected object field reflected light distribution information of each area is calculation-processed by predetermined multi-pattern algorithm, thereby determining such a degree of weighting to each of the divided areas that optimum exposure is provided to the main object. Subsequently, immediately after the shutter is opened, the flash apparatus is caused to effect main flashing, and light reflected by the surface of the film is caught a plurality of same photoelectric converters as said photoelectric converters, and the weighting whose degree has been determined is effected on the outputs thereof, and then the outputs are summed and integrated, and the flashing of the flash apparatus is stopped at timing determined by the integrated value being compared with a predetermined value, thus terminating the flash control of the main flashing. That is, the quantity of emitted light is determined at timing for stopping the flashing of the flash apparatus. The TTL flash control system of this camera system, i.e., a TTL flash control system involving preliminary flashing, will hereinafter be referred to as the "TTL multi-flash control". In contrast, a TTL flash control system which does not involve preliminary flashing will hereinafter be referred to as the "TLL ordinary flash control".
When it is desired that the technique of TTL multi-flash control disclosed in this Japanese Patent Application No. 1-203735 be evolved in the actual camera system, both of the camera body and the flash apparatus be endowed with predetermined new functions. That is, it is necessary that the camera body have a photoelectric converter capable of effecting split photometry, an output signal processing circuit, a sequence controller, etc. and that the flash apparatus have a device for repetitively effecting preliminary flashing and main flashing within a short time and controlling the quantity of emitted light so as to limit the maximum quantity of emitted light in preliminary flashing in order not to reduce the ability of main flashing very much.
However, the camera body and the flash apparatus which are endowed with the new functions are in relality also connectable to those of the conventional type and in such a combination, photographing can be accomplished only under the TTL ordinary flash control of the conventional type. Particularly, when flash photographing is to be effected with a flash apparatus of the conventional type which is capable of TTL ordinary flash control mounted on a camera body having the TTL multi-flash control function, the impression of a useless possession is undeniable.
Also, when TTL multi-flash control photographing is possible, loss of some energy is unavoidable even if a contrivance is made to limit the quantity of emitted light during preliminary flashing as described above, and there is a demerit that the guide number during actual photographing is reduced.